Plant load regulating system



July 22, 1941. c. c. LEV 2,249,840

PLANT ow REGULATING SYSTEM Filed llarchi, 1940 2 Sheets-Sheet 1v fig \ j a Z, i

v" 757 19.6: Load.

WITNESSES: INVENTOR I Cyri/CLevy.

BY I I ATTORNEY A Z/LW 7 M July 22, 1941. c. c. LEVY. ,3

PLANT LOAD REGULATING SYSTEM Filed March 2, 1940 2 Sheets-Sheet 2 wlTNEssEs: INVENTOR L y/"fl C. L evy.

f ATTORNEY Patented July 22, 1941 UNITED STATES PATENT orrrcs Pittsburgh. Pa, assignor to Westinghouse Electric & Mann! acturing Company,

East Pittsburgh. Pa, a corporation Pennsylvania Application March 2, 1940, Serial No. 321,893

4 Claims. (of. 111-119) This invention relates to load reg l ting sy tems for controlling the load or d electric power consumed by a customer. Due to the economies of electric power generation and power companies are. desirous of maintaining a continuous constant load on their available equipment must always be sui'ilcient to maintain the'load at the peak value required and, it this is used only tor a short period of time throughout the 24 hour period, the equipment remains idle without advantage to the company. Consequently, many industrial plants electric power are required to pay at a higher rate if the total power consumed exceeds a predetermined agreed upon value, as determined either by wattmeters or demand meters measuring the power consumed.

Certain industries carry loads oi! a character which makes it economical to automatically vary the load to certain apparatus as the load on other ap tus varies in order :to maintain the power consumed at a substantially constant value within the limit in which the lower power rates are available to the customer. 7

Many plants in the electrochemical industry.

$ 885. The

- response of the this type oi equipment possesses several advanadiustment oi the output voltage from such apparatus can be made without the necessity of operating movable contacts as is required in the case output voltage to the adjustment or the regulator is substantially instantaneous and the controlled power required ior operation or the regulator equipment is very small.

In view oi the advantages above pointed out, a regulator system of the above-indicated character may be operated with the primary controlled element of the system set closer to the permitted maximum load available to the consumer than would otherwise be possible because a smaller margin is required between this maximum load and the permitted power consumable for example, lend themselves to automatic plant I load regulation since these plants consist of a heavy base load of electrolytic cells and a smallor varying plant load comprised 01' motors, lights, etc.

The electrolytic cell load may readily be varied without appreciable inconvenience to the satisfactory operation of the equipment and thus equalize the demand, the load supplied to the cells being regulated to nil in the smooth out the peaks of the power consumption curve. Regulating systems available for regulating such plant extensive use as might be because the existing systems do not have the sensitivity and accuracy desired in order that the benefits of automatic regulation be fully realized.

The load should preferably be regulated automatically at some predetermined value such as the kilowatt value which when exceeded for an appreciable time, would result in a penalty to the power purchaser. It a regulator system can maintain this kilowatt load with great accuracy, the penalty is avoided and at the same time the maximum kilowatt input is obtained for the electrochemical load.

The electrochemical load should preierably be supplied through an ignitron rectifier unit since loads have not come into as at the lower rate.

It is an object of the invention to provide a plant load regulator system that controls the load supplied to a power consuming plant that is sensitive to small variations from the desired value in which the adjustment in power consumed takes place substantially instantaneously and in which the power required for controlling the system is small.

Other objects and advantages or the invention will appear from the following description or one preferred embodiment of the invention, in which Figure l is a and apparatus diagrammatic view of circuits illustrating an embodiment of the invention;

valleys and v Figs. land 3 are diagrammatic views or circults and apparatus that may be substituted for certain controlled parts 0! the equipment illustrated in Fig. 1.

Referring to Figure 1, an alternating current power circuit having conductors I, 2 and 3 is illustrated for supplying current to a plant transformer having primary windings t and secondary windings 5 to supply current to .the plant load indicated generally as comprising an alternating bank 6 and a direct current load supplied through conductors I and 8 through ignitron rectifier units 9, i0 and H as controlled by igniter tubes i2, i3 and I4, respectively.

The alternating current load supplied from the transformer bank 8 may be 01' a character that is not readily controllable and may consist, for example, of certain motor and lighting loads that are to be employed as the necessities of the operation of the plant dictate.

of rotating machinery. The

load supplied througha transformer This load may vary well within the total power desired from the alternating current source, which power may be maintained substantially constant by regulating the power supplied to the direct current load of the plant through conductor I and 8. For the purpose of regulating the power supplied through the alternating current circuit represented by conductors l, 2 and 3, a primary regulating device, indicated generally by the numeral ii, is provided and comprises two wattmeter elements i6 and ii diiferentially related to each other for applying torque in opposite directions to a shaft l8. The polyphase wattmeter element l8 comprises voltage windings IB and 22 connected to power circuit conductors i, 2 and 3 through a polyphase potential transformer 23 and current windings 24 and 25 connected to current transformers 26 and 21, respectively, as shown.

The reference load wattmeter element l1 comprises voltage windings 28 and II connected to conductors Si, 32 and 33 which are supplied with energy, at a constant potential as controlled by a voltage regulator 34, from conductors I. I and 31 that are connected to the secondary windings oi the plant distribution transformer. The wattmeter element I1 is also provided with current windings 38 and I! that are connected in series with resistors 4i and 42 connected to conductors 3| and 33, respectively, and which serve as a reference load. The movable shaft i8 of the primary control element I actuates a movable vane 43 which, together with the stationary vanes 44 and 45, form a variable condenser which is used as the control element in the grid circuit of a controlled tube 4 for governing the igniter tubes I2, 13 and i 4 which, in turn, control the igniters 9, i0 and ii, to thereby control the direct current power supplied to the circuit comprising conductors 1 and l. The tube 43 is illustrated as having an electron emitting cathode 41', an anode 48 and a control grid electrode 49. The cathode 41 is supplied from a low voltage winding 5i 0! a transformer having a primary winding 52 connected to conductors I3 and 54 of an alternating current source and having a secondary winding 55 that supplies a circuit consisting of a resistor 58 and a capacitor 5?. Current passes through the anode circuit of the tube 46 from conductor 53 through the conductor 68, through the tube to cathode 41 through a reactor 59, resistor ii and conductor 82 to the alternating current conductor 54. The reactor 58 in series with the resistor ii and two condensers 63 and 54, connected in shunt relation to the resistor Bi between conductor 62 and the opposite ends of the reactor 58, together serve to reduce the ripple in the output from the tube 48. The potential 0! the control electrode 40 is determined by a circuit including a conductor 85, the capacitor comprising vanes 43, 44 and 4!, conductor 66 and resistor 58 that is connected to the tube cathode 41. The operation of the tube 46 controls the voltage drop across the resistor H which acts as a load on the tube and one end of which is connected to the conductor I of the direct current load circuit.

The ignitrons 9, i0 and H are provided with anodes 61 connected by conductors II to the outer ends of a secondary winding ll of a main power transformer shown as of the Y-connected distributed type, the neutral point 72 of which is connected to the direct current conductor 8. The main power transformer is provided with a primary winding 13 inductively related to the-secondary winding N. The ignitrons 9, ll and H are also provided with mercury pool cathodes 14 connected to the positive conductor 1 o! the direct current load circuit and providedwithlgniters II that are connected to the cathodes ll of igniter tubes I2, II and I4, respectively.

The igniter tubes l2, II and H are provided with anodes 18 that are connected by conductors II to the outer terminals of a Y-connected distributed secondary winding 82 of a charging transformer having primary windings II and to the neutral point 84 or the secondary winding with which the conductor 1 is connected. The igniter tubes l2, II and [4 are likewise provided with control grids ll that are connected by conductors 88 to the outer terminals or a three-phase grid transformer secondary winding l1, the neutral point ll 0! which is connected by a conductor II to a selected point on the resistor II. The primary winding ll of the grid transformer is inductively related to the winding 81. The grid circuit for the igniter tubes II, II and i4 extend from their respective cathodes 11 by conductors 18 through igniter 15 of the associated ignitron tubes to conductor I, a portion 0! resistor ll, conductor 89, the several phase'windings oi! the grid transformer I! and conductors II to the respective grids ll.

In the operation 01' the above-described appsratus comprising a plant load regulated system, the resistors 4| and 42 provide a phantom or re!- erence load measured by the wattmeter element I! that applies a torque to the shaft il in opposition to the torque applied by the wattmeter element I. that is responsive to the actual load on the alternating current circuit I 2 and 3. The diilerential variation in the torque developed by the wattmeter elements I. and I1 determines the movement of the capacitor vane 43 to vary the capacitance in the above-traced circuit from the cathode 41 to the control electrode 4O 01' the control tube 44, to thus vary the conductivity oi the tube 40 and consequently the voltage impressed across the resistor 4|. The voltage drop across the portion 01 the resistor ll between conductors I and is applied in the above-traced grid controlled circuit or the igniter tube II, II and H to determine the time of firing of the ignitrons 9, l0 and II and thereby the current output therefrom in a well known manner.

It will be apparent, therefore, that movement of the shaft ll 01' the primary control device ll varies the capacitance in the control electrode circuit of the tube 46 to render that tube more conducting or less conducting, to thus increase or decrease the negative grid bias developed between conductors l and II across the selected portion of resistor CI, to thereby control the conductivity oi the igniter tubes I2, I! and i4 and the output current 01' the ignitrons 0, II and II in a direction to increase or decrease the direct current load supplied to the circuit conductors 1 and 8 to thus maintain the total plant load supplied through conductors i, 2 and I substantially constant irrespective of variations in the load drawn from the transformer bank l by the alternating current devices comprising a part of the equipment oi the plant.

Referring to Figs. 2 and 3, the equipment shown may be substituted for the control tube 4| and its immediately associated circuits in Fig. l, and the variable capacitor comprising the vanes 4!, 44 and 45 may be employed with the circuit arrangements shown in Figs. 2 or 3. to directly vary the grid bias voltage applied between conlated to a secondary winding I04 across which a condenser I is connected in shunt. A tube I06 is provided having a cathode I01 energized from a transformer I08 connected between conductors IM and I02. The tube I06 is provided with an anode I09 connected by a conductor III to one end of a transformer primary winding II2 to an intermediate point II3 of which the winding I04 is connected. The tube I06 is also provided with a. control grid III connected in a grid circuit extending from the cathode I0'I through the transformer winding I04 to the junction point H3, 8. portion of the transformer winding II2, conductor H5, condenser H6 and resistor H1, in parallel, to the grid I I4. A condenser H8 is connected in shunt to the winding II2, which winding is inductively related to a transformer secondary winding ii I. The oscillator circuit abovedescribed operates in a well-known manner to provide a fixed frequency which may have a value between 100 and 400 hilocycles which serves as a source of supply to the secondary winding I2I supplying a bridge circuit including resistors E22 and I23 connected in parallel circuit relation across the winding MI and in series, respectively,

with capacitor elements C1 and C2 which may correspond substantially to the vanes 43, 44 and 45 shown in Fig. 1. If the resistors I22 and 23 are of equal value. and the capacitors C1 and C2 are equal, the bridge will be balanced. capacitors C1 and C2 are arranged to be varied in opposite directions, that is, so that the capacitance of one increases while the capacitance of the other decreases upon operation of the primary control device 25, a voltage will be supplied through conductors PM and I25 to the full-wave rectifier I26 for applying a control grid bias to the grid circuit of the exciter tubes I2, l3 and It.

The purpose of the oscillator in Fig. 2 is to provide a frequency high enough to permit the capacitors C1 and C2 to be of relatively small microfarad. capacity. In Fig. 3, a fill-cycle supply circuit, represented by conductors I21, is shown, the capacitor elements Ci and 02 being connected through transformers I28 and I20 which step up the voltage applied to the capacitors C1 and C2 to a. high value, thus permitting theuse of small capacity condensers at low frequency.

Many modifications in the circuits and apparatus illustrated and described will appear to those skilled in the art, and I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention: 1. In a load regulating system, in combination,

If the an alternating current circuit, power consuming devices supplied from said circuit, electronic rectifier means for supplying unidirectional energy from said circuit to certain of said devices, and means for controlling the power output of said electronic rectifier including a grid control circuit, an adjustable capacitor in said grid control circuit, means for varying said capacitor comprising a pair of difierentially related power measuring elements, one of which is responsive to the power fiow through said alternating current circuit and the other of which is responsive to the power desired in said alternating current circuit.

2. In a load regulating system, in combination, an alternating current circuit, power consuming devices supplied from said circuit, electronic rectifier means for supplying unidirectional energy from said circuit to certain of said devices, means for regulating the power flow in said alternating current circuit comprising electronic tube means for controlling said rectifier, a grid control circuit for said tube means, a pair of adjustable capacitors for controlling said grid circuit and diflerentially related measuring means differentially responsive to the power fiow in said alternating current circuit and a phantom circuit for establishing the desired power flow in said alternating current circuit.

3. In a load regulating system, an alternating current circuit power supply source, a load circuit, apparatus supplied from said source including grid-controlled rectifier means for supplying unidirectional current to said load circuit, a grid control circuit therefor including an impedance device, means including a grid-controlled control tube for varying the voltage component across "said impedance device, a control-grid for said control tube and a variable capacitor for controlling the conductivity of said tube, a primary control device for adjusting said variable capacitor and having two differentially related watt elements one of which is sensitive to the power from said alternating current circuit source and the other of which is sensitive to a reference load circuit.

4. In a load regulating system, an alternating current power supply source, ignitron type rectifiers for supplying electric energy to a unidirectional current load circuit from said source, gridcontrolled igniter tubes for controlling the output current from said rectifiers, variable capacitor means for controlling said igniter tubes, a primary control device for adjusting said variable capacitor and having two differentially related watt element one of which is sensitive to the power from said alternating current source and the other of which is-sensitive to a reference load circuit.

CYRIL C. LEVY; 

